1. Field of the Invention
This invention relates to the cutting of full-sized, substantially tree-length "stems" by means of a manual, semiautomatic or automatic saw carriage or carriages, typically in connection with a stem handling apparatus which is designed to deliver the stems to the saw carriages or modules for cutting into segments of optimum character. The linearly adjustable saw carriages of this invention typically operate in a preferred automatic mode with respect to a fixed carriage in cooperation with a scanner for determining the physical characteristics of incoming stems in sequence, a computer for receiving the scanned information and selecting optimum stem cuts and a programmable logic controller for receiving data from the computer and executing commands to orchestrate operation of the respective adjustable and fixed saw carriage functions. The adjustable saw carriages are pre-positioned for optimum cutting of each stem by means of a module drive assembly and encoder assembly connected to the programmable logic controller and include rollers for receiving and positioning the stems against a butt plate for indexing the stems, clamps for stabilizing the stems in position prior to cutting, swinging circular saws for cutting the clamped stems in concert at the optimum locations determined by the computer and ejection mechanisms for ejecting the cut stem segments, typically onto a conveyor for further processing.
One of the problems associated with "bucking" or handling tree-length logs, or "stems" of various size and shape with an infinite pattern of sweep, knots, depressions, twists and other defects and cutting the stems into properly sized logs, poles and other segments for further processing, is that of effecting optimum cuts for each stem in order to provide an optimum stem value from the segments. various scanning devices and mechanical means for achieving this purpose have been developed in combination with log bucking saws, slasher decks, debarkers and like equipment. A primary problem associated with these systems is the complexity of the cutting equipment required and the accompanying slow feed and processing time required to initially determine the optimum cuts in the stem and subsequently effect these cuts in an efficient manner to produce stem segments of optimum length. Added to the problem of slow processing and handling time is that of the considerable down-time required for maintenance purposes, which maintenance down-time is a function of the complexity of the equipment used to process the stems into logs and other segments.
2. Description of the Prior Art
Various log "bucking" and cutting systems are known in the art. U.S. Pat. No. 4,468,993 dated Sep. 4, 1984, to Jack R. McCown, et al, details a "Small Log Bucking System" in which a log is scanned to determine its size and shape, the resulting data are analyzed by a computer which determines the optimum location for cuts and the proposed cut locations are displayed on the log optically for the operator's inspection. If the operator overrides any of the proposed cuts, the computer re-calculates any cuts not specified by the operator. When all cuts have been approved, the log is kicked to a cutting bed where the cuts are made by two, independently controllable travelling saws. The cutting bed is preferably defined by three sets of parallel plates, the first set of which includes stationary plates having V-shaped upper edges which define a V-shaped trough in which the log is initially received. The second and third sets of plates are vertically movable and, when raised together, define a second V-shaped trough located above the first trough. After the logs are received in the first trough, the movable plates are raised to elevate the log to the second trough, where it is cut. After each cut is effected, the movable plate supporting the downstream side of the cut-off segment are lowered to allow the segment to roll onto an output conveyor, which carries it to the next work station. In this manner, the segments are automatically singulated without a separate singulating station. U.S. Pat. No. 4,640,160 dated Feb. 3, 1987, to John E. Hards, details a "Sweep-Data-Responsive, High-Speed Continuous-Log-Travel Bucking Apparatus". The system features continuous log travel and includes a flying-saw, log-bucking mechanism in combination with an upstream scanner which is capable of producing data related to a log "sweep". A computer which is interposed between the bucking mechanism and the scanner makes a decision at least partially based on log-sweep data, as developed by the scanner, to determine the optimum bucking position or positions along the log length to obtain the maximum recovery of useable end product. A "Log Scanning System" is detailed in U.S. Pat. No. 4,907,294, dated Mar. 6, 1990, to William E. Bolton, et al. The bucking operation includes a log deck with logs delivered laterally onto a log stem holder and from the holder onto the conveyor chain for conveying the log stems in sequence through the bucking saw. The log stem holder constitutes a component of a scanning station. An overhead support has a carriage that is guided along the holder and scanners carried by the carriage obtain dimensional data of the vertical and lateral dimensions of the log stems at selected cross-sections. A laser beam transmitter on the carriage transmits the data to a stationary computer mounted at one or both ends of the scanning station.
It is an object of this invention to provide one or more improved, simple and efficient linearly-adjustable saw carriages for cutting stems into segments of desired length, which saw carriages may be linked to a scanner, a computer and a programmable logic controller to automatically cut incoming, previously evaluated stems into logs, poles and other segments of optimum length for further processing.
Another object of this invention is to provide at least one, and preferably multiple, linearly-adjustable saw carriages and a single, fixed saw carriage for cutting stems which may be automatically evaluated and cut by at least the following elements: an optical scanning device for analyzing the physical characteristics of incoming stems in sequence; a computer for receiving the scanned data and determining optimum stem cuts; and a programmable logic controller for controlling the various saw carriage functions, including linear adjustment of the adjustable saw carriages. In a preferred embodiment, the separately linearly-adjustable saw carriages are each fitted with an encoder and a companion spur gear drive system mechanically connected to the encoder. The encoder and spur gear drive system are electrically connected to the programmable logic controller for adjusting the movable carriages with respect to the sequentially loaded stems. The fixed and movable carriages further including stem rollers, stem clamping devices, a swinging circular saw and segment-ejecting mechanisms, each orchestrated by the programmable logic controller, for receiving a stem from a loading apparatus, adjusting the stem against a butt plate provided on the fixed carriage to a common cutting orientation, clamping the stem in place, cutting the stem into segments of selected or optimum length and ejecting the segments from the saw carriages, typically onto a conveyor for transport to further processing.
A still further object of this invention is to provide a new and improved fixed saw carriage and at least one linearly-adjustable saw carriage, the latter oriented for linear adjustment with respect to the fixed saw carriage. The saw carriages are typically computer-controlled and as such, operate in cooperation with an optical scanner for determining the physical characteristics of incoming stems in sequence, a computer electrically coupled to the scanner and a programmable logic controller electrically connected to the computer and to an encoder assembly and a fluid-operated spur gear module drive assembly. The programmable logic controller controls the various functions of the saw carriages by orchestrating the carriage positioning encoder system and module drive assembly in the movable saw carriages for linear adjustment of the movable saw carriages with respect to the fixed saw carriage. The programmable logic controller also orchestrates operation of the respective fluid-operated roll drives, clamp arm positioning cylinders, saw positioning cylinders and stem-ejecting cylinders provided in each one of the linearly-adjustable saw carriages and the fixed saw carriage, as well as the fluid-operated butt plate positioning cylinder in the fixed saw carriages. The movable saw carriages are preferably mounted on rails to facilitate precise positioning of the corresponding carriage cutting saws adjacent to a stem loading platform.